1. Field of the Invention
This invention relates to two-dimensional code, which is designed based on the specifications of high resolution CCD(Charged Coupled Device) scanning unit to achieve high density data storage and improving rate of recognition.
2. Description of the Prior Art
Various two-dimensional codes have been developed. One known two-dimensional code is to form of a matrix containing data having a first side and a second side each being formed of identical broken line patterns, and a third side and a fourth side are each formed as a solid line of equal darkness intersecting at a second corner. The solid lines correspond to the length, height and area of the code. At this two-dimensional code, the matrix data elements were divided into multiple parts to build up in two-dimensional array for error correction as disclosed in Japanese Patent Laid-Open Publication No. 168902/1995.
Another known two-dimensional code is to use special shape of timing cell as the image capture devise which should be embedding in a matrix data elements for obtaining quick response of image by CCD(Charged Coupled Device) scanner, disclosed in Japanese Patent Laid-Open Publication No. 254037/1995.
The above-mentioned trials were found to be useful to capture the image of two-dimensional code by the CCD scanning equipments with low-resolution specification such as 380,000 pixels which to be used for reading conventional one-dimensional bar code. The main concentration of designing those two-dimensional code were how to retrieve physical size and position of two-dimensional code, and importance of storing and recording of large amount of data elements into a restricted area was not considered due to low performance in resolution of CCD scanner.
However, these trials premised on low performance in resolution of CCD scanner are now blocking to store high density matrix data elements in limited space, because of their structure of timing cells which have to be embedded in the matrix data elements area for obtaining quick response of two-dimensional code image. Therefore, processing area of two-dimensional code has become larger in size according to ratio of information amount when trying to store large amount of data element.
Owing to recent technical innovation, especially remarkable development of high-resolution CCD digital cameras and high performance DSP (Digital Signal Processor), environment has been consolidated to store large amount of information with high density in a restricted area. By adopting current high technology achievement, it became possible to capture the data of two-dimensional code in high speed by the current high resolution CCD image scanner and DSP without using special timing cells or multiple array matrix data arrangement.
This invention is proposed considering the above mentioned innovation of technology and, a new type of two-dimensional code is designed that is able to obtain higher speed of reading and higher density of information.
This invention is designed to solve the above-mentioned problems by following means.
By this invention, it is composed of matrix data elements area where the binary data are encoded to a two-dimensional code and a continuous solid line to cover four corners and center part of the matrix data elements area, and this two-dimensional code is provided with a pattern to give information of both data density of the above matrix data elements and physical size, and the above pattern, applied with a solid line to adjacent of an area of matrix data elements, is arranged to pass four corner points from upper side to two corner points of bottom side going through the center point of right and left side such as the line in alphanumeric Z shape or S shape.
The solid line that reaches to the fourth corner, and the final part of the solid line is further extended to the same length of capture line(projection part). Thus only the fourth corner point is projected toward outside as per a register mark of commercial printing, which can be selected as the datum point to specify position coordinate within reading image.
On a solid line of the above pattern, capture lines(projection part) at a fixed pitch are allocated as outward extension of solid line, however no capture lines locates on the solid line that crosses the area of matrix data elements. Since the capture lines are allocated based on the volume of storage information, density information of the data can be judged by calculating amount of capture lines that are located by a fixed pitch on a solid line. By this way, information of data density of matrix data element area can be obtained.
Owing to this invention, physical size of code can be specified by a solid line which covers all four corner points of matrix data element area, and by allocating the above pattern that provides information of data density on a solid line, physical size and density information of two-dimensional code can be identified by a single pattern. Therefore improvement of reading speed of this two-dimensional code is realized, and this two-dimensional code can be presented that can contain large amount of information into higher density.